Issue: Are structure queries needed?

We have previously described that DASL cannot deal with XML structures
easily. For example, this problem arises with the lockdiscovery property.
This problem prevents us from solving a simple scenario: list all the
resources that are not collections. We then proposed several solutions for
this.

I would like to revisit the one I feel: (1) solves this scenario, (2) does
not raise the bar for server implementations, (3) does not attempt
standardize non-existent practice, and (4) is extremely localized (has no
impact to other properties).

I propose a property that simply evaluates to TRUE or FALSE depending on the
type of resource.

Somewhat more formally ....

The "DAV:iscollection" property evaluates to TRUE if the DAV:resourcetype
property contains the element "DAV:collection", and FALSE otherwise. 

Thus, I propose we punt for the time being any more complicated operators.
Scenarios we have identified that tunnel into XML are, IMO, not as
funadmental as this one.

Comments?

-Saveen